AP Environmental Chapter 6

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Terms in this set (...)

All the individuals that belong to the same species and live in a given area at a particular time, boundaries are hard to define

Levels of Complexity

Individual < Population < Community < Ecosystem < Biosphere

Community

All of the populations of organisms within an area, boundaries hard to define

Ecosystem

All the biotic and abiotic components of a region, contains communities

Biosphere

Incorporates all of the ecosystems, on a global scale

Population Size

Immigration + births - deaths - emmigration = ___________- Also known as n- The total number of individuals within a defined area at a specific time.

Population Ecology

The study of factors that cause populations to increase or decrease

Population Density

The number of individuals per unit of area (or volume of water) at a given time

Population Distribution

A description of how individuals are distributed with respect to one another- Three Types:--Random, like trees--Uniform, like farms--Clumped, like schooling fish

Sex Ratio

Ratio in a population between males and females, usually close to 50:50 in sexually reproducing populations

Age Structure

A description of how many individuals fit into a particular age category- Large proportion of reproducing age -> rapidly growing population

Density-Dependent Factors

Factors that influence an individual's probability of survival and reproduction in a manner that depends on the population size

Limiting Resource

A resource that a population cannot live without and which occurs in quantities lower than a population would require to increase in size

Carrying Capacity

Limit of how many individuals the food supply can sustain (k)

Density-Independent Factors

Factors that have the same amount of effect on an individual's probability of survival and reproduction at any population size (like tornadoes, hurricanes and volcanoes)

Growth Rate

The number of offspring an individual can produce in a given time period minus the deaths of the individual or offspring in that same time period

Intrinsic Growth Rate

Maximum potential for growth specific to the population (r)

Exponential Growth Model

N(t)=Noe^rtN(t): Population size after t timeNo: N sub 0 or the current populationr: intrinsic growth ratet: time

J-Curve

When population growth is very rapid and exponential it is modelled by a ____________

Logistic Growth Model

A population whose growth is originally exponential but then slows as it reaches the carrying capacity of the environment, looks like an s-curve

Overshoot

When food does not match population size and it is larger than the carrying capacity

Die-Off

A population crash, commonly after an overshoot

k-Selected Species

A species with a low intrinsic growth rate and the population size increases slowly to carrying capacity. Population fluctuations are small.- Typically large organisms that are reproductively mature later and life- Have few, large offsprings and the parents provide a substantial amount of care

r- Selected Species

A species with a high intrinsic growth rate that reproduces frequently with many offsprings.- Typically have population shoot ups and die offs- Usually small, reproductively mature quickly

Survivorship Curves

Distinct patterns of survival over timeType 1: approach old age and then die of in large numbers (k- Selected species)Type 2: Constantly decline over timeType 3: Population starts high but many die off in their early life and few reach adulthood (r- Selected)

Corridors

Strips of habitat that connect separate populations

Metapopulations

A group of spatially distinct populations that are connected by occasional movements of individuals

Community Ecology

The study of interactions (competition, predation, mutualism and commensalism), which determine the survival of a species in a habitat

Competition

The struggle of individuals to obtain a limiting resource (bad for both sides)

Competitive Exclusion Principle

Two species competing for the same limiting resource cannot coexist

Resource Partitioning

Two species divide a resource based on differences in the species behavior or morphology- When competition reduces the ability of a species to survive and reproduce, natural selection will favor individuals that overlap less with the other species in the resources they use

-- Temporal: Reducing competition by using the same resource but at different times-- Spatial: Reducing competition by using different habitats--Morphological: reducing competition by the evolution of different body shapes and sizes

Predation

The use of one species as a resource for another speciesFour Types:- True Predators: typically kill their prey and eat most of it (lions)- Herbivores: consume plants as prey (deer)- Parasites: live on or in the animal they consume (tapeworms), or pathogens (parasites that cause disease in the host)- Parasitoids: organisms that lay eggs inside other organisms, larvae then consume the host inside out, eventual death of the host

Mutualism

Benefits two interacting species by increasing both species chances of survival and reproduction (plants and pollinators)

Commensalism

A relationship in which one species benefits but the other is neither harmed nor helped ( birds using trees as a perch)

Symbiotic Relationship

The relationship of two species that live in close association with each other

Keystone Species

Species that play much more important roles in communities that the relative abundance suggests

Predator- Mediated Competition

When a key predator prevents another species from taking over and allows for other species

Ecosystem Engineers

Keystone species that create or maintain habitat for others

Ecological Succession

The predictable replacement of one group of species by another over time

Succession that occurs in areas that have been disturbed but have not lost their soil, like places after hurricanes, forest fires, abandoned farms etc.Annual weeds > perennial weeds and grasses > shrubs > aspen, cherry and pine forests > beech and maple broadleaf forests

Pioneer Species

Species with the ability to colonize new areas rapidly and grow well in full sun.

Aquatic Succession

This term covers the kinds of the the following two types:- Ocean: algae on rock > barnacles > barnacles and mussels- Lakes: open water lake > accumulating sediments > filled in and terrestrial

Theory of Island Biogeography

Dual importance of habitat size and distance for richness.- Large habitats: more species, less prone to extinction, wide range of habitats- Closer, more species